Electric time indicator for sounding apparatus



Dec. 7, 1937.

A. M. J. LABOUREUR ET AL 2,101,076 ELECTRIC TIME INDICATOR FOR SOUNDING APPARATUS 2 Sheets-Sheet 1 Original Filed May 11, 1932 i 3a {27 $0 4/ 42 32 is as I W' 43 I I 35 7b 77%? [ND/CH me a mwa A 61;, G! M1 Jr es. 7, 1937. L, A. M. J. LABOUREUR ET AL 2,1 ,07

ELECTRIC TIME INDICATOR FOR SOUNDING APPARATUS Original Filed May 1 1, 1932 2 Sheets-Sheet 2 7 2 ec zmma /zeiza reZaj.

Patented Dec. 7, 1937 UNITED STATES PATENT OFFICE ELECTR IC TIME INDICATOR FOR SOUNDING APPARATUS Louis Auguste Marie Joseph Laboureur, Paris, and Raymond Dubois, Asnieres, France This invention relates to an electric time indicator for air and submarine sounding apparatus which is based upon the measuring, by means of a triode, of the charge acquired by a condenser between the emission of a sound and the receiving of the echo of said sound, said charge representing the measure of the time elapsed between said emission and said reception and consequently the distance between the sending point and the 0 surface of the soil or the bottom of the sea which has generated the echo.

This application is a division of our application Serial No. 610,676, filed May 11, 1932.

A first characteristic feature of the invention .5 consists in that the condenser is included in a circuit which comprises: a resistance fixing the charging speed, a potential difference serving for the charging and the grid-filament space of the triode, the latter acting as a one way conductor which allows the charging of the condenser but not the discharging thereof.

Further, according to the present invention the charging of the condenser is started by a connection characterized by a discharge neon lamp connected firstly to a source of electrical potential, secondly to a transformer, causing it to light by the eifect of the sending of the short signal, thirdly to a resistance included also in the transformer charging circuit and at the terminals of 39 which the potential difference utilized for charging the condenser exists, said difference being due to the ohmic drop in the resistance brought about by the current passing through the neon lamp.

Another characteristic of the invention con- 3', sists in that the end of the charging period of the condenser is controlled by an excess voltage in opposition to the electromotive force of the source that feeds the neon lamp and consequently starts the extinction of the lamp.

The excess voltage is produced by the rectifying cf the alternating current (having the same frequency as the sharp sound emitted as the signal) due to the sound efifect of the echo which has been received; the rectifying device being 45 connected in series in the circuit which comprises the neon lamp and its feeding source.

Another characteristic of the invention consists in the use of a delaying connection constituted by a neon lamp placed at the terminals of 79 a condenser which is charged through a resistance from the moment of emission and which causes the lighting of the lamp when its charging pressure reaches the critical ignition value, the lamp circuit comprising a primary transformer 55 winding the secondary of which is connected i 6 Claims. (Cl. 161-15) the circuit of the first neon lamp whose ignition starts the charging, so that it cannot begin before the direct reception of the emitted sound.

This avoids the untimely extinction of the first neon lamp which would be caused by the direct reception of the emitted sound if said lamp was lighted as soon as the sound is emitted.

The appended drawings show diagrammatically a mode of construction of a time indicator according to the present invention. In order to facilitate the understanding the drawings illustrate also a sound emitter and an echo receiving device.

Fig. 1 is a vertical sectional view of the soun emitter.

Fig. 2 illustrates diagrammatically the echo receiving connections.

Fig. 3 is a diagrammatic view of the time indicator which is joined to the connection shown in Fig. 2.

Referring to the embodiment of the invention illustrated in Fig. 1 the sound emitter comprises a whistle l, a balanced valve 2, a horn 3 and contact pieces constituted by two conducting rods 4, 5 retained in recesses 6, I by means of springs 8, 9, in contact with the end portion IU of the rod of the velvet.

An insulated part I I is set in the valve stem end Ill in order to avoid all electrical contact between the parts 4 and 5 when the valve stem is in the position corresponding to open.

The object of the contact, which is consequcntly closed when the valve itself is closed and opens when the valve is open, is to start the operation of the time indicator hereinafter described. I2 is an inlet pipe for the admission of compressed air from a tank (not shown).

The valve is constituted by two cylindrical elements operating as pistons I3 l3 between which is formed a chamber l4 allowing the passage of compressed air when the valve is in the position shown in Fig. 1 where it uncovers the openings l5, l6. When the valve is displaced to the right or to the left it closes the openings I5, Hi. This movement of the valve may be produced either by actuating the rod 11 by means of an electromagnet ll, or by means of a percussion hammer which has not been represented in the drawings as it may be of ordinary construction. The rod ll ensures also the guiding without wedging of the pistons 13 l3 in a cylinder I8 which is periorated with holes I9 to avoid compressing a;

useless air cushion at the ends.

It will be noted that at starting the valve is closed either towards the right or the left and that the whistling is produced by the displacement of the valve from one of its end positions, for example from the left to the right.

During this movement, the air pressure delivery can take place only when the valve passes its middle position.

The sound emitted by the airship or the submarine boat is reflected back by the ground or the sea bottom, the echo being received by a microphone 21 (Fig. 2) which is connected at 30 and 3| with the amplifier illustrated in Fig. 2.,

In this apparatus the connections between the vacuum tubes are effected by transformers having a high coefficient of magnetic leakage produced by placing side by side a primary coil 35 and a secondary coil 36 a bundle of straight ferromagnetic plates passing through them and connecting them together.

The secondary coil is designed so as to be resonant to the signal frequency when it is connected across a condenser 31 having a capacity of the order of 0,1 to 5/1000 microfarad.

The primary coil 35 comprises a number of windings such that its self reactance may be compared to the internal resistance of the vacuum tube that feeds it but preferably lower.

The vacuum tube 28 shown in Fig. 2 is an amplifier and the vacuum tube 29 is both an amplifier and a detector. 30" is a terminal connected to the. microphone and to the negative terminal 39 of the filament heating source. The return from the microphone is through terminal 3! to the primary 32 of a transformer of the kind shown in Fig. 3 having a secondary 33 tuned by the condenser 45.

The anodic current passes through the primary 35 of another tuned transformer (secondary 36 with tuning condenser 31) connected to the positive heating terminal 38 and to the detecting grid by a condenser 42 of a few thousandths microfarad shunted by a resistance of about 1 to 4 megohms.

The time indicator system is connected to the terminals 43-44 in the plate circuit of the tube 29.

The terminals 43- of the time indicator system are also shown in Fig. 3. In this figure the .condenser, the charge of which will serve to measure the intervals of time, being the condenser 50, its electrode 5| is connected to the grid of a triode lamp 52 which is very thoroughly exhausted and insulated. The filament of this lamp is heated by a source of voltage 53 of 4 volts.

The other electrode 55 of the time indicator condenser 50 is connected to the negative end 55 I of the filament of the triode lamp 52 by'means of a resistance R1 having a well determined value and whose function is to determine the constant of the charging period of the condenser.

Between this resistance R1 and the negative end 55 of the filament is "placed another resistance R2 put in a hereinafter described circuit which comprises neon lamps.

The operation of the time indicator part of the system is as follows:

During the whole interval'of time to be measured, a continuous current I (delivered by the circuit in which the neon lamps are placed) flows through the resistance R2 and causes at its terminals an ohmic drop of the value RzXI such that it tends to make the grid positive relatively to the filament and for this reason said voltage RzXI is applied to condenser 50 owing to the conductivity of the space grid-filament of the triode.

During the time to be measured, owing to the cause if it were not so the lamp being well insulated would not be the seat of any grid current and as the latter is precisely the loading current i itself, the term Rixi would be nil, so that the grid tension would be the same as RzXI which is very positive and generally rises to several scores of wits and would therefore with stronger reason be positive.

It is well known that when the grid of a triode lamp is positive a current which may reach several milliamperes, passes inside the triode between the iilament and the grid.

For positive tensions of about a fraction of a volt, the grid current is sufficient to prevent the charging current being limited by the inner gridfilament resistance, but rather by the outer resistance R1 placed in the condenser charging circuit.

This results more especially from the fact that when the gridis positive the grid-filament space may be likened to a resistance inferior to 100.000 ohms and even for existing lamps, inferior to 50.000 ohms.

Consequently when the outer resistance R1 is of the order of several megohms it may be said (as a first approximation) that everything takes place as if the lamp were used as a short circuit and connects to the point 55 of the filament the electrode 5| of the condenser 50 which is connected to the grid.-

During the time interval to be measured the condenser 50 charges itself according to an exponential law and as at the end of the time to be measured I becomes equal to zero, the potential diflerence RzXI disappears. The grid potential which had been made positive owing to the tension R2 I only, immediately becomes negative. The discharging current stops itself immediately because the space grid-filament acquires too time to be measured.

The triode grid having thus acquired a negative potential measuring the condensers charge, the anodic current of the lamp acquires a value which corresponds to said potential and remains stationary, the grid potential itself remaining unchanged as no discharging takes place.

The relation that determines the value of the plate current in. function of the grid tension is well known-and remains unchanged for a given lamp (this being the anodic characteristic of the lamp). Consequently the deviations of the milliamperemeter M are characteristic of the charge acquired byv the condenser and are consequently a function of the time during which the current Ipassed through the resistance R2.

The connections which allow of sending the current I in the resistance R2 during the inter- Val to be measured will now be described.

A closed circuit is formed which comprises a neon lamp 56 connected to the resistance R2, an alternating current rectifier constituted by a transformer 51 and a system of copper oxide rectifying rings forming a Wheatstone bridge 58.

The primary 59 of transformer 51 is fed by the current coming from the selecting amplifier shown in Fig. 2 to which the receiving microphone 21 is connected.

The reception of the echo signal is expressed by an alternating current in primary 59 which produces in the secondary 60 an alternating tension then rectified in the rectifier 58 and applied between the terminals 58 58 inthe direction that tends to render the neon lamp 56 positive relatively to the terminal 58 of said rectifier.

The leading-out terminal 56 is connected to the secondary 6| of a transformer 62, which is connected in its turn to a potentiometer 63- fed by a battery 64 and allows the introduction into the circuit of a potential difference which may vary from about 0 to 24 volts. This voltage is applied in the direction opposite to the continuous voltage produced by the rectifier 58.

Between two terminals 65, 66 of which the first is connected to the positive terminal of the potentiometer 63 and the other to the terminal 61 of resistance R2, there isapplied a constant voltage of the order of volts which may be produced by a storage battery for which a lighter battery 68 may be substituted in order to reduce the weight of the plant in view of its utilization upon airships.

Considering that the voltage of a battery may not be quite constant and that the value of the current I passing in this circuit must be strictly constant, it has been found advantageous to stabilize the voltage produced between the terminals 65, 66 by the utilization of the steadying properties of a discharge neon lamp. -That type of lamp having the well known property of maintaining a constant voltage at its terminals from the moment of its ignition when a current which may vary from a few microamperes to a few inilliamperes is caused to pass through it.

Consequently electric current'from the battery 68 of about volts in series with a resistance R: of the order of 100.000 ohms will be sent through theregulating lamp 69. A current of about 4/10 of a milliampere for which the voltage at the terminals is substantially constant and of the order of about 84 volts is thus caused to pass in this neon lamp. This voltage depends moreover on the neon lamp used, but is well defined for every lamp.

The battery 68 is comprised between the terminals 65, I0, the negative end being connected to the terminal 65 and the positive to the terminal 10 which is connected to the resistance R: connected itself at 66 to the regulating neon lamp 69.

Considering now the circuit 56, 58, 6|, 63, 65, 66, 61, 56 it will be seen that it is the seat of a constant electromotive force tending to cause a current I" to flow in the direction shown by the arrow through the resistance R2.

This constant voltage is equal to E+V, E being the constant voltage at the terminals of the neon lamp 69, and V the voltage at the terminals of the potentiometer 63.

When the neon lamp 56 is out thisvoltage E+V is wholly applied upon its terminals. Now it is 'well known that a neon lamp ignites at certain voltage U and goes out at another voltage U lower than U Consequently if the total voltage E+V is between U and U the lamp will remain lighted as long as no circumstance outside the circuit has caused one of both limit voltages to be overstepped.

In order to operate the time indicator at the beginning of an interval of time, an excess voltage will be produced in the neon lamp circuit 56 in the direction which increases the existing voltage. The critical ignition voltage U will thus be bridged over and the neon lamp will light up acquiring then a very weak inner resistance which may be considered small relatively to the resistance R2 which may be chosen without inconvenience of the order of about 200000 ohms.

In these conditions a permanent current will flow in the resistance R2 under the action of the permanent electromotive force E+V which still exists when the sudden disturbance which started the ignition has disappeared.

This disturbance is caused as will be further explained by the sending of the sharp signal but with a certain delay, which is always the same;

When the echo caught by the microphone, selectively amplified by the amplifier and rectified by the rectifier 58 reaches the apparatus, it produ'ces an opposing voltage in the circuit of the neon lamp 56. This excess of voltage reduces the electrcmotive force E+V to the point of making it lower than the extinction voltage U of the lamp 56. This results in the lamp being extinguished; and the current passing through R2 ceases.

Having now indicated how a constant current I may be started in the interval of time to be measured, that is between the instant when the emission is started and that when the echo stops, it, we now describe the part of the connection which produces the excess ofvoltage due to emission and the ignition of the neon lamp 56.

The neon lamp 56 will be lighted with a constant delay which is determined once for all relatively to the sending of the sharp sound; thus the direct reception of the whistle signal will be without inconvenience because as the neon lamp is not lighted its extinction cannot be produced.

Moreover, the system designed to delay the igniting excess of voltage will be such that it will produced it during the time of measurement but will not produce any reverse excess of voltage.

This result is obtained by the ignition of a third neon lamp H, mounted in series with the primary winding 12 of the transformer 62, by the action of a source of current which may be the same as that 68 already mentioned between the terminals 65, 10.

In order to delay the ignition of the neon lamp 1 l the progressive charge of a condenser 13 interposed between the tern inal T4 of the transformer 12 and the terminal I5 01' the neon lamp II will be utilized. The terminal 14 is connected to the terminal 65, negative end of the battery 68.

The terminal I5 connects the other plate ofthe condenser '13, onthe one part to the neon lamp H and on the other part to the blade contact 16 of a relay 1! fed by the current from a source I8, the circulation of whichis controlled by the contact 4, 5 carried by the whistle valve.

The relay 1! is of the multi-contact-telephone type and comprises a locking contact 80 which closes when the current closes the relay and thus keeps it constantly energized- The valve contact 4, 5 is mounted in series with opening of the contact 4, 5 completely interrupts the current and consequently the relay is no longer operative. I

A push button 19 which shunts the operating contact 80 allows when the whistle is not operating, the closing of the circuit to the source 18 through contacts 4, and causes operation of the relay 11 which could not otherwise be operated as the open contact 80 by which it is operated is in series with the source 18.

Consequently the closing of the relay may take place before the sounding operation and this relay will thus remain operating until a sudden interruption of the contact l, 5 will cause the interruption of operation of the relay 11 which will not be capable of re-operating itself.

When operating the relay l'l closes another contact 8|, completely independent of the others and short-circuits the condenser 50 placed in the grid circuit of the measuring triode 52, so that the latter is always completely unloaded before any measuring takes place and it remains short circuited up to the very moment of starting said measuring.

The relay 1'] also actuates in the aforesaid manner the blade 16 which reciprocates between two blade is connected to the other terminal of said condenser. I

When the relay is operating which is the case before the beginning of a sounding operation, the contact 1683 short circuits the condenser I3 which is thus completely discharged.

At the instant when a sound is emitted owing to the displacement of valve 2 (Fig. 1) its con.- tact l-5 interrupts the passage of the current in the relay I1 and de-energizes it, this breaking on the one part the contact 8| which short circuited the time indicator condenser 50 and causes on the other part the displacement of the blade 16 which moves away from the abutment 83 against which it was pressed by the permanent closing of the relay, to come to rest upon the abutment 82 where it will remain as long as the re-energization of the relay is not effected positively by means of the push button 19.

From the moment when the blade putting the condenser 13 in short circuit has engaged the contact 82, this condenser begins charging throu h the resistance R4 under the action of source 68.

The charging voltage acquired by the condenser 13 increases according to an exponential law up to the moment when it reaches the ignition voltage of the neon lamp H.

At that instant the lamp lights up instantaneously producing in the winding of the transformer 62 a current inflow which thus produces the excess voltage that starts the ignition of the neon lamp 56 (beginning of the time interval measured by the time indicator).

The lamp 1| then remains lighted, the voltage of the source 68 which is higher than the ignition voltage being sufiicient to keep the lamp H lighted.

Consequently no opposing excess voltage caused by the transformer 62 can be produced during the sounding operation, the current produced in the neon lamp circuit remaining constant. The

incoming of the echo causes the extinction of the neon lamp 56.

As above stated, the mllliamperemeter M indicates the anodic current of the triode and by its deflection, shows the time during which the time 5 indicator condenser has been charged when the measuring is ended.

When it is desired to retiu'n the whole system to its starting state it will be necessary only to actuate the button 19, this operation re-starting the feeding of the relay 11, short circuiting again the time indicator condenser through contact 8|,

operation the lamp H is again put out like the 20 lamp 56.

It will be noted that the measure of the charging time of the time indicator condenser difiers from the time which has elapsed between the emission of a signal and the reception of its echo only by the time during which relay 11 operates and the charging period of condenser I3.

Both intervals of time are constant and it will be sufiicient to take them into account once for all by fixing them separately. In practice the calibration or marking of the time indicator is' determined wholly by experiment.

The milliamperemeter graduation giving the measure of the anodic current may be given directly in time intervals or in meters whenmeasuring the distance. I

In stating the principle of the time indicator a certain number of numerical values chosen so as to allow operation of such an apparatus have been mentioned but these values are not limiting as their. choice depends on the individual properties of different types of discharging lamps as well as on the time intervals to be measured. They may be calculated according to the principles above stated and may consequently be modified without departing from the limits of our invention.

What we claim and desire to secure by Letters Patent of the United States is:-

1. An electric time indicator comprising: a condenser, a triode lamp having a filament, a grid, and a plate, a source of plate tension, a source of filament tension, a condenser charging circuit comprising a resistance, a source of constant potential dlfierence and the filament to grid space of the said triode lamp and including said condenser, said space functioning as a unilateral conductor permitting the charge of the condenser but preventing its discharge; means for starting the charging of the condenser, means for stopping said charging at the end of the phenomena to be measured, and means for measuring the variation in anodic current of the triode lamp under the action of the charge acquired by the condenser, from the variation of which the time is measured.

2. An electric time indicator according to claim 1, characterized in that the means utilized for establishing the. constant potential difference in the condenser charging circuit comprise: a fixed resistance through which passes a constant current, said resistance being interposed in a circuit which compries a neon discharging lamp, means to prevent said lamp from lighting until a predetermined interval following the beginning of the phenomenon to be measured, and means for causing it to be extinguished at the end of said phenomenon.

3. An electric time indicator according to claim 1, characterized in that said means for starting the charging of the condenser comprise a neon discharging lamp which is situated in said condenser-charging circuit; a transformer, said means for starting the charging of the condenser including the secondary winding of said transformer, which is situated in said condensercharging circuit; a primary-transformer circuit comprising the primary winding of said transformer, and means for producing a current therein at a predetermined interval following the beginning of the phenomenon to be measured; said source of constant potential difierence comprising a fixed resistance through which passes a constant current, said fixed resistance being situated in said condenser-charging circuit; said means for stopping the charging of the condenser at the endof the phenomenon to be measured causing an extinguishment of said neon lamp at the end of said phenomenon.

4. An electric time indicator according to claim 1, characterized in that said means for starting the charging of the condenser comprise a neon discharging lamp which is situated in said condenser-charging circuit; a transformer, said means for starting the charging of the condenser including the secondary winding of said transformer, which is situated in said condensercharging circuit; a. primary-transformer circuit comprising the primary winding of said transformer, and means for producing a current therein at a predetermined interval following the beginning of the phenomenon to be measured; the last-mentioned means comprising a second neon lamp, a contact for closing the primary-transformer circuit and a relay to close said contact; a condenser connected in parallel with said secondary winding and said second neon lamp; said source of constant potential diiierence comprising a fixed resistance through which passes a constant current, said fixed resistance being situated insaid condenser-charging circuit; said means for stopping the charging of 'the condenser at the end of the phenomenon with current at the end of the phenomenon to be measured to cause an extinguishment of said lamp.

6. An electric time indicator according to claim 1, characterized in that said source of constant potential difference comprises a battery and a fixed resistance, said battery and said resistance being situated in said condenser-charging circuit; and a neon lamp connected in parallel with said battery and said resistance and supplied with current from said battery.

LOUIS AUGUSTE MARIE JOSEPH LABOUREUR. RAYMOND DUBOIS. 

